Subject: [homenet] On mif and classifying prefixes

From: Steven Barth <[email-masked]>
Date: Tue, 28 Jul 2015 22:53:55 +0200

(x-post mif / homenet)

Hello everyone,

little backstory: when I learned about the multiple interfaces problematic
in homenet, I was introduced to it with the anecdote of smartphone apps with
"use over 3g", "use only on wifi" settings and at some point there was
draft-bhandari-dhc-class-based-prefix-05 which sort of tried to define some
generic properties (e.g. "not for internet usage", "usage is charged", ...)
for prefixes as well as a (more or less?) opaque "class" identifier.
Now that draft is expired for >1.5 years and mif seems to occupy that niche.

So to my understanding (and what I got as feedback on the mic a few days ago),
mif is (atm?) (exclusively?) about explicitly identified provisioning domains,
and not about generic classification of prefixes and / or interfaces. That means:
to actually use a provisioning domain I need to know the PVD-ID beforehand.
There is no way for anyone not knowing the PVD-ID to guess what is inside, not
even to the degree of "this is (not) for internet connectivity". Ideally from
what I would have expected is that my applications may actually want to cope
with multiple unknown prefixes and select a suitable one based on some generic
"metric" (e.g. "high bandwidth" or "low latency" or "low cost" etc.),
or maybe even just the basic "this is metered cellular connection" vs "this is
unmetered broadband" would seem to me as a good start.

So is what I am asking for out of scope for mif? Am I supposed to collect a
database with all PVD-IDs to know what's inside? Is there any other way to do
this? At least to me this explicitly known PVD-ID case seems important but
a rather small aspect of the whole classification of address prefixes matter,
especially for what I think homenet is concerned.

Cheers,

Steven